As people's demand on the light transmittance, resolution, power consumption and so on of display devices are higher and higher in recent years, all of the display devices are developing toward the direction of high transmittance, high resolution, low power consumption, etc. The higher the resolution is, the smaller the size of each pixel unit is. When the side length of a pixel unit is changed from several tens of micrometers to a dozen micrometers, if the width of a black matrix for partitioning pixel units still remains unchanged, then relative to pixel units, the black matrix will become apparent, and this will affect the display effect of the display device.
Therefore, an integrated technology (namely, Color Filter on Array, briefly called as COA) in which color filters and an array substrate are integrated together emerges as times require. Because a black matrix is situated on an array substrate in this case, while the width of the black matrix is appropriately decreased, it can also be ensured that gate lines, data lines, thin film transistor units and other structures in need of shelter against light can be fully shaded by the black matrix. Moreover, the possibility that a light leakage phenomenon occurs is reduced, and the display effect of the display device is guaranteed while the resolution and transmittance are enhanced.
As discovered by inventor(s), after the black matrix is integrated onto the array substrate, in view of the fact that the black matrix is usually situated between a drain electrode of a thin film transistor and a pixel electrode, in order to achieve the electrical connection between the drain electrode and the pixel electrode, it is required that a via hole be formed in the black matrix. This via hole will have an influence on the shading effect of the black matrix on the drain electrode, and this causes the drain electrode to reflect light from the via hole side. Thus, the display effect of the display device is degraded.